Tag Archives: Ethiopia

Ethiopia Sidama Dereje – A couple of disasters

Lots of work this weekend on the RoastGenie — I now have the sample camera working.  All the roast profiles will have small snaps of the roasted beans.  The camera is a standard Raspberry Pi camera with the focal length adjusted for close up shots.  The resolution is fantastic – probably does not come across all that well in the profile plots though. I will post more on that later.

Today I roasted three batches of Ethiopia Sidama Dereje which ended up being an object lesson in the hazards of software bugs.  A tiny error in code caused the heater to turn off right after first crack.  I suspect these will be _really_ bad but thought I give them a rest and a taste just for reference.


Although not on my profile plots just yet, I have set the RoastGenie up to calculate development ratio (time past 1st crack / total roasting time).  I’ve not studied this carefully yet but I’ve read a little that suggests numbers between 20 and 25% are ideal.  The roast above has a development ratio of 18%.  This is probably a little higher than it actually was though since I let the roast go a little while before I realized it was actually cooling — normally this cooling time would not count.

A second roast shows the same bug.  I stopped this one as soon as I realized the heater had cut out.  It has a development ratio of 11%.


And finally a proper roast:


This one started from a very well heated roast chamber (heated to ~500F for 10 mins or more then cooled just until inlet temp was at 200F).  First crack was very well defined and energetic.  Stopped this  one well before second crack.  Development ratio was a respectable 21%.